092: Add SECP256K1 Signature Support

[bakarezainab]

#092: Add SECP256K1 Signature Support

Category: [CONTRACT]
Difficulty: ● MEDIUM
Tags: soroban, signature, secp256k1, compatibility, security

Description

Extend the contract's signature verification to support SECP256K1 (Ethereum-style) keys in addition to Stellar's default ED25519. This allows for broader compatibility with hardware wallets and cross-chain bridging tools.

Acceptance Criteria

• Integrate Soroban's verify_sig_secp256k1 built-in function.
• Update authorization logic to recognize non-Stellar address types.
• Benchmark CPU instructions for SECP256K1 vs. ED25519.
• Document the requirements for signing payloads for this key types.